da SteF1 » 24/11/2024, 11:22
altro estratto dal libro di Newey. Re-incollo sotto la parte che ho messo giorni fa, per completezza.
That said, there’s no doubt in my mind that his major preoccupation
was the fact that he hadn’t yet won a race. He wasn’t one to apportion
blame. If anything, he was too quick to take responsibility for things that
weren’t his fault. But this was his championship bid and he was yet to
score a single point. He knew we were trying to understand the car, and
he listened patiently and understandingly as I explained to him what I’d
seen at Nogaro, and how I thought the problem was the sidepods,
explaining that we were designing new ones, that a solution was in hand.
At the same time, we’d done what we could to address an ongoing
issue he had with his seating position, where he felt cramped and was
rubbing his knuckles on the inside of the cockpit. Why this was
happening I’m still not sure. His hand position on the wheel must have
been different from that of his predecessors or teammates. Either way,
he wanted the steering wheel lowered slightly to give more knuckle
clearance.
The job was to move the steering wheel down by a couple of
millimetres, but we had to bear in mind an FIA regulation template,
which was an aluminium plate with a width of 200mm and height of
200mm. Ofàcials had to be able to pass it between the driver and the
inside of the cockpit, from his upper body down to the pedals. If this
wasn’t possible, your car was declared illegal and excluded.
If we lowered the steering column, then the template wouldn’t pass.
The solution was to reduce the diameter of the steering column locally
by 4mm, which is what we’d done.
At the track, however, there was still this ride problem to address.
More in hope than expectation, we àtted softer springs, but that just
meant bigger changes in ride-height, which in turn aggravated the
aerodynamic instability. We tried running the front higher, but lost too
much downforce. I still had hair then. I was raking my àngers through
it, trying to ànd the answer, knowing in reality that the problem was
more profound than anything we could tackle at the track. We were
trapped with a bad car. No amount of set-up tuning with springs,dampers or roll bars was ever going to overcome its aerodynamic instability.
What we could see once we were allowed to inspect the steering
column was that it did have a fatigue crack present, so it was going to fail
sooner or later. It had fatigued roughly a third of the way around the
circumference and the rest had snapped, either in the impact or from the
pressure Ayrton exerted while trying to control the car after the rear
stepped out. Where the steering column failed was where it had been
locally reduced by 4mm in diameter.
This led to the further question: would the remaining two-thirds of
the column that had not fatigued have had enough strength to transmit
the torque required to maintain normal driving? So we built a test rig
consisting of the complete car steering system, and, with a saw, cut onethird of the way through the new column to represent the fatigued area.
We then got a ‘driver’ to turn the steering wheel in order to achieve the
highest pressure shown by the data recorder. The result was that, yes,
even in this damaged state, the column had enough strength left in it.
Following that result we conducted various tests, trying to marry data
recovered from the ECU for pressure transducers across the steering
rack and the steering column data with measurements on the rig. When
the car left the edge of the circuit, it travelled across a very uneven
boundary from circuit to apron, which put large pressure spikes across
the rack with corresponding spikes in the column torque. The only way
we could achieve the column torques on the rig was with the column still
reasonably intact and thus able to transmit torque due to the rotational
inertia of the steering wheel – put simply, a completely broken column
could not be made to register any steering column torque readings.
Now, I am responsible for following that request of Ayrton’s to lower
the steering wheel slightly to avoid him rubbing his knuckles on the
inside of the chassis. I am responsible for giving the drawing ofàce the
instruction to lower it by 2mm, and when they came back to me to say
that it would then interfere with the FIA cockpit template, I instructed
them to reduce the steering column diameter locally by 4mm.
What I didn’t do was look at the detailed drawing myself or have a
proper checking system in place to make sure that it had been done in a
safe manner. It’s a simple, well-known law of engineering that tomaintain stiffness and strength you have to increase wall thickness, but
that wasn’t done. The wall thickness was not increased.
It’s also a simple, well-known law of engineering that if you have a
very sharp corner in a component, that causes an area of very high
stress; and because of that stress, the component will eventually crack
and fatigue; and that fatigue crack will propagate eventually around the
whole component and cause failure.
So there were two very bad pieces of engineering in that diameter
reduction. Ultimately, Patrick and I were responsible for that.
You question yourself. If you don’t, you’re a fool. The àrst thing you
ask yourself is: Do I want to be involved in something where somebody can
be killed as a result of a decision I have made? If you answer yes to that
one, the second is: Do I accept that one of the design team for which I am
responsible may make a mistake in the design of the car and the result of
that mistake is that somebody may be killed? Prior to Imola, stupid as this
may sound, I had never asked myself those questions.
If you want to continue in motor racing, you have to square that with
yourself. You have to be prepared to offer an afàrmative to both of
those questions because, try as you might, you can never ever guarantee
that a mistake will not be made. Designing a racing car means pushing
the boundaries of design. If you don’t, it won’t be competitive. Then
there’s the decision-making during the race. If a car is carrying damage
for some reason, you have to make the decision: Do I tell a driver to retire
the car or let him continue? If you call it too conservatively, you simply
retire the car for no good reason. If you’ve been too bullish, the driver
could have an accident with unknown consequences. It’s never an easy
judgement.
People ask me if I feel guilty about Ayrton. I do. I was one of the
senior ofàcers in a team that designed a car in which a great man was
killed. Regardless of whether that steering column caused the accident
or not, there is no escaping the fact that it was a bad piece of design that
should never have been allowed to get on the car. The system that
Patrick and I had in place was inadequate; that cannot be disputed. Our
lack of a safety-checking system within the design ofàce was exposed.
So, in the immediate aftermath, Patrick and I discussed that and
agreed we would have to go to a category system in which the safetycritical components, including the steering system, braking system,
suspension parts and key aerodynamic components such as the front
wing and rear wing – all the things that, if they failed, could cause an
accident – should be submitted to an experienced stress engineer who
would look at the drawings, make sure they were structurally sound and
then countersign the drawing.
What I feel the most guilt about, though, is not the possibility that
steering column failure may have caused the accident, because I don’t
think it did, but the fact that I screwed up the aerodynamics of the car.
per chi volesse, il libro si trova tranquillamente in rete, in inglese. Basta scrivere "pdf".
